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Old 31st March 2008, 11:24 PM   #9
Roger
Dream Team - School Guru
 
Join Date: Aug 2006
Posts: 2,112
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Hi Unregistered,
In some cases there may be no difference, in other cases there may be quite a bit of difference.
Constant curve masts have about a 13% bend ratio.
How/where each loft specifies the top and bottom bends to equal 13% can vary significantly.
Some are softer in the top, but not so soft that the are "flex top".
Some are very constant curve and are as close to 13% throughout their entire length as it's posible to make them.
On the very high end of the spectrum, Powerex makes their own 100% Z-Speed masts.
Severne and Sailworks (and probably some others that I'm not familiar with) have their 100% carbon race masts made by Italica in Italy. Very nice masts but also very costly.
Each loft has masts made to their specifications and they test them to ensure that the company that makes them meets their specs.
Almost all std. dia masts are now constant curve so there may not be too much difference.
I use Powerex Z-Speeds, Sailworks Lightsticks (Itallica), Sailworks Speedsticks (Powerex), and Severne Redline (also Itallica) masts pretty much interchangeably, but there are minor differences in the way the sail looks, but nothing I have been able to detect on the water.
You will always "tune" your rig a bit, and when tuning you will focus on what you want.
More power= less downhaul and less top twist.
Better gust handling = less draft lower in the sail, more top twist.
Better high wind stability= more downhaul, more top twist, more panel tension top to bottom and a bit more outhaul to stabilize things.
So, to get the optimum performance (as designed into the rig by the loft) you probably will not go wrong using the recommended "best" mast, and this will always give you the best "starting point".
If the mast meets the design specs. (not all of them do) you can pretty much rig "by the numbers".
From there you will need to figure out what characteristics are the most important for you, on your boards, in your conditions. Then tune your rig to your personal specifications.
As far as which masts are "better", I would say the Powerex has consistently been the mast that more lofts specify as the "best alternate mast" if the loft has it's own brand.
If you use several different brands of sails and don't want to buy several different masts to go in them, then the Powerex masts seem to have the widest application range.
If you want to "rig by the numbers" then you are better off to buy the mast recommended as "best" from the loft that designed your sail.
The only other way to find out would be to get the "best" mast from the loft that designed your sail, and the "best alternate" mast from wherever, and have one of the high end sail lofts run a series of bend tests between the 2 different masts.
And, the results may vary depending on how the test is performed.
Some lofts run their tests with a simple weight at the 25%/50%/75% test points (with the mast suspended 5 cm from each end. This is the standard "Mast Check System" methodology.
Other lofts have gone to a jig that pulls the bend into the mast from the ends (just as downhauling does) and the results are different from the std. mast check system methodology.
Hope this helps,

Last edited by Roger; 1st April 2008 at 12:25 AM.
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